The present invention relates to a method of mixing a plurality of gases and more particularly to an improved technique for minimizing the possibility of explosion during the mixing of such gases as hydrogen and oxygen.
In particular arts, it is often necessary to provide a homogeneous combination of gases by mixing a plurality of individual gases. By way of example, the diving art requires that a different combination of gases be employed as dives are made to greater depths. Generally, the use of air as a diving gas has been limited to the 250-300 foot range where the occurrence of nitrogen narcosis begins to inhibit diver efficiency. Pure oxygen exhibits toxic effects at depths greater than 150 feet and has therefore also been unsuitable for use in deep dives. Consequently, the primary breathing gas for diving purposes has been a mixture of helium and oxygen for depths greater than 200-300 feet. In this combination, the helium provides a suitable breathing mixture with oxygen by inhibiting narcosis at diving pressures and exhibiting a lower solubility than nitrogen in both fatty and aqueous tissues to thereby reduce the decompression time needed to avoid "the bends". However, for deep and long duration dives, large amounts of helium are required. Since the supply of helium is limited, the cost has increased significantly as the demand has increased, thereby making the use of helium economically prohibitive.
As an alternative, hydrogen has been proposed as a substitute for helium in deep and long duration dives. Hydrogen provides similar benefits to those of helium by reducing the effects of narcosis and exhibiting a low density for easy breathing. In addition, even though hydrogen is more soluble than helium or nitrogen, it has a higher diffusivity which can be advantageous for long duration dives. However, in spite of the fact that the technology has been available to inexpensively produce and safely handle and store hydrogen as a liquid, its use with oxygen as a diving mixture has been restricted due to the explosive nature of hydrogen-oxygen mixtures having a percentage of oxygen greater than 6 percent.
As is known, in order to provide for the possible mixing of hydrogen and oxygen, the 6% oxygen limitation must be maintained at all times in order to avoid the possibility of explosion. In any mixing technique, however, there tends to be a volume of the mixture which will initially have a higher concentration of one gas until the other gas is dispersed evenly throughout the total volume. Therefore, while a variety of techniques have been proposed to enable the mixing of such gases, none have been able to reduce the danger of explosion below an acceptable level so that an on-site generation of the diving mixture could be safely employed. There is thus a continuing need to provide inexpensive techniques for mixing a plurality of gases and, more particularly, for enabling the use of hydrogen as a diving gas wherein its use with oxygen would normally produce an explosive combination of gases.
Accordingly, the present technique has been developed to overcome the specific shortcomings of the above-known and similar techniques and to provide an improved system for mixing precise quantities of hydrogen and oxygen.